Cavansite

A brilliant blue mineral found in 2001 in Eastern Iceland has been confirmed as being cavansite, an extremely rare mineral found only at a scattering of sites around the world.

The chemical formula for cavansite is Ca(VO)(Si4O10).4H2O. Cavansite has an orthorhombic crystal structure; its crystals are prismatic. Cavansite has avitreouslustre and is a brilliant sky blue or blue-green. Its hardness falls between 3 and 4 on the Mohs scale, meaning that it is somewhat harder than calcite. Its cleavage {010} is good.

Cavansite is a very rare mineral, found only at a handful of sites in the world. The mineral was first described in 1968 (Malheur County, Oregon, USA). Owyhee Dam in Oregon is the type locality for cavansite, although the largest and best samples come from Pune District in India, where cavansite is found alongside pentagonite, calcite, heulandite, stilbite, apophyllite, thomsonite and mordenite in cavities and fissures in tuff and breccia. In Iceland, the mineral has been found in tuff alongside calcite, heulandite and stilbite.

The mineral's name is drawn from the chemical elements from which it is composed: calcium (ca-), vanadium (-van-) and silicon (-si). In Iceland, vanadium is found mainly as a trace element in magnetite and pyroxene. Minerals containing vanadium are often noted for their appearance. Indeed, Vanadís is another name for Freyja, the goddess of beauty and love in Norse mythology.